With accelerating climate change and the urgent need to stack polygenic traits, multiplex CRISPR/Cas offers a scalable route to resilient crops-yet low editing efficiency and regeneration bottlenecks remain critical constraints. This review centers on multiplex strategies for polygenic trait engineering in plants, surveying compact nucleases (Cas9, Cas12, Cas13 and emerging ultra-compact variants), polycistronic gRNA platforms (tRNA-gRNA arrays, self-cleaving ribozymes, Csy4 processing), and delivery routes (Agrobacterium, biolistics, protoplast transfection, viral vectors). We highlight concrete outcomes-for example, targeted edits in PYL ABA-receptors increased rice grain yield by up to 31% in field tests-and applications from yield and disease resistance to abiotic-stress tolerance, nutrient biofortification and de novo domestication. Technical risks (off-targets, mosaicism, chromosomal rearrangements, transformability) are appraised alongside emerging fixes: compact/engineered nucleases, RNA-processing arrays, morphogenic regulators, and AI-driven sgRNA design integrated with multi-omics. By prioritizing multiplex approaches for polygenic trait stacking, the review argues that these tools are essential to accelerate precision breeding for climate-adapted agriculture.
